Extreme weather events – Signs of climate change?

The first half of 2010 was the warmest period since meteorological records began in 1880.

Germany experienced its fourth warmest July, with temperatures averaging 20.2°C, which is 3.3°C higher than the climatological average (16.9°C). The consequences were all too evident: unable to cope with the heat, the air-conditioning broke down on a number of Intercity Express trains. Power stations were forced to reduce output when river temperatures exceeded critical thresholds and the required degree of cooling could no longer be guaranteed.

In Russia, 50 people died in July when fires caused by heat and drought spread to villages, forests and peat bogs. The final number of heatwave victims is not yet known. On 29 July, Moscow registered its highest temperature since records began 130 years ago: 37.8°C. Other parts of Russia reported temperatures of 40°C and more.

In Pakistan, the temperature reached 53.5°C in May, breaking the existing Asian record. Since 22 July, many parts of Pakistan have been plagued by floods which have claimed over 1,100 lives. Hundreds are still missing and over 30,000 people have been forced to flee their homes. In all, the floods, Pakistan’s second worst ever, have affected more than 1.5 million people.

Signs of climate change?
A single weather event is not proof of climate change but the sum total of events

constitutes a clear chain of evidence which is backed up by additional meteorological readings. March, April, May and June 2010 were the warmest ever recorded globally, and July looks set to follow suit.

Another sign of global warming is that the area covered by sea ice in the Arctic Ocean shrank to record lows in June and July, and is expected to reach a new absolute minimum in September. This is happening even against the background of minimum solar activity during the first six months of 2010 and indicates that solar radiation can be excluded as a causal factor for the extreme weather events.

These facts show that global warming is playing a significant role in the rising number of extreme events. Analyses performed by Munich Re’s natural catastrophe database, the most comprehensive in the world, substantiate this increase: the number of extreme weather events like windstorm and floods has tripled since 1980, and the trend is expected to persist.

Excerpts from interview with Prof. Peter Höppe, Munich Re’s Head
of GeoRisk Research/Corporate Climate Centre,
on ZDF TV news program (Germany), 09.08.2010

Munich Re has been analysing natural hazards and natural hazard losses for more than 35 years. For this purpose, Munich Re has set up the most comprehensive natural catastrophe database in the world, which currently comprises more than 28,000 events. It documents major events from 1950 onwards, all claims-related events from 1980 onwards, and the effects of natural catastrophes on individual economies, the insurance sector and the population.

Loss trends
“Our database clearly indicates a sharp rise in the number of weather-related natural catastrophes per year, in terms of overall and insured losses. For instance, there has been a threefold increase in floods since 1980. There has also been a rise in the number of windstorm losses, Atlantic hurricanes being particularly destructive.”

“In Germany, extreme precipitation resulting in floods is becoming increasingly common. This affects not only people living on rivers: there are more and more cases of heavy rain and flash floods. Anyone may be affected.”

“Both the hundred-year flood in 2002 and the current flooding on the River Neisse were caused by what are referred to as Vb weather conditions, that is to say, a low-pressure system from the Mediterranean region which passes to the east of the Alps and then heads south again. This produces extreme precipitation on the northern slopes of the Alps and low mountain ranges. This situation has occurred much more often in recent years – and explains a substantial proportion of the many floods in Poland, the Czech Republic, eastern Germany and parts of the Alpine Foreland.”

Current weather extremes and climate change
“Climate change cannot be identified from individual events but our figures, backed by verifiable changes in meteorological data, indicate a trend towards an increase in extreme weather events that can only be fully explained by climate change.”

“The current state of knowledge leaves no doubt about the existence of anthropogenic climate change. Whether the current weather extremes are caused or intensified by climate change is uncertain, but there is considerable evidence indicating that climate change is involved at least to some extent.”